filtration device

Abstract

The present invention provides a filtration device that can efficiently obtain filtered water while suppressing the suction and pressing pressures acting during filtration and backwashing operations, and can ensure stable filtration functionality over a long period of time. [Solution] In a filtration device 1 configured by stacking multiple filtration modules 2 in the vertical direction, each module comprising a plurality of membrane elements 4 arranged at predetermined intervals from one another in the left-right direction, and a water collection cassette 6 connected to the rear end of each of the plurality of membrane elements for collecting filtered water flowing inside each membrane element, the water collection cassette has horizontal passages 31a, 32a extending along the direction of arrangement of the plurality of membrane elements and having a circular cross-section, and vertical passages 41a, 42a, 43a connected to the horizontal passages and extending in the vertical direction and having a circular cross-section, the vertical passages are configured to communicate with the vertical passages of the water collection cassettes of other filtration modules arranged above and / or below.

Description

Technical Field

[0001] The present invention relates to a filtration device in which filtration modules having plural membrane elements are configured to be stacked in plural stages in the vertical direction, and particularly relates to the structure of a water collecting part for collecting filtered water filtered by the membrane elements.

Background Art

[0002] Conventionally, as this type of filtration device, for example, the one described in Patent Document 1 is known. The filtration module (referred to as "membrane module" in Patent Document 1) of this filtration device includes plural membrane elements each formed in a flat plate shape and arranged in parallel with a gap therebetween, and a pair of water collecting parts (referred to as "water collecting members" in Patent Document 1) provided at both ends of these membrane elements.

[0003] Each membrane element has a filter plate whose front shape is a horizontally long rectangular shape, and flat membrane-shaped filtration membranes respectively attached to the front and back surfaces of this filter plate. A large number of flow-through holes penetrating in the front-back direction are formed in the filter plate, and plural horizontal flow paths each extending in the left-right direction and arranged at intervals in the vertical direction are formed. At both left and right ends of the filter plate, plural permeate outlets opening to the corresponding water collecting part side are provided in a vertically aligned state, and each permeate outlet is continuous with the end of the above-mentioned horizontal flow path.

[0004] On the other hand, each water collecting part is formed in a box shape, and the wall surface on the membrane element side is constituted by a membrane element fixing plate. Plural slits extending in the vertical direction are provided in the membrane element fixing plate, and the left and right ends of the membrane element are inserted into these slits and joined to the membrane element fixing plate by thermal welding. Further, in each water collecting part, an upper water collecting port protruding upward is provided at the center of the upper wall, and a lower water collecting port opening downward is provided at the center of the bottom wall.

[0005] The filtration modules configured as described above are arranged in a stacked configuration in the vertical direction. Specifically, each filtration module is connected such that both water collection sections are fitted to those of the upper and lower filtration modules, and the upper water collection port is fitted to the lower water collection port. As a result, both water collection sections of each filtration module are in communication with the corresponding water collection sections of the upper and lower filtration modules.

[0006] This filtration system, composed of multiple stacked filtration modules, is installed in a treatment tank containing the liquid to be filtered. During filtration, negative pressure is applied by a pump to the uppermost filtration module's upper collection ports on both sides. As a result, in each filtration module, the filtrate filtered by the filtration membranes on both sides of each membrane element flows through the flow holes in the filter plate into the lateral channels, and into the collection ports on both ends of these lateral channels, i.e., the left and right sides. The filtrate that has entered each collection port then flows into the upper collection port via the upper and lower collection ports, and finally is discharged to the outside of the filtration system through the collection ports of the uppermost filtration module. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2011-101869 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the filtration module described above, the water collection sections on both sides of the multiple membrane elements are formed in a box shape. Therefore, a relatively large suction force must be applied to the water collection sections during filtration, which may reduce the efficiency of obtaining filtered water. Furthermore, during backwashing, when washing water or washing air is flowed through the filtration module in the opposite direction to filtration to clean each membrane element, a relatively large pressure must be applied to the box-shaped water collection sections to introduce the washing water or other substances. If large suction or pressure is applied to the water collection sections of the filtration module during filtration or backwashing, the filtration module may be damaged, potentially reducing its filtration function.

[0009] The present invention was made to solve the above-mentioned problems, and aims to provide a filtration device that can efficiently obtain filtered water while suppressing the suction and pressing pressures acting during filtration and backwashing operations, and that can stably ensure the filtration function over a long period of time. [Means for solving the problem]

[0010] To achieve the above objective, the invention according to claim 1 is a filtration device configured by stacking multiple filtration modules in the vertical direction, each comprising: a plurality of membrane elements, each formed in a flat plate shape extending in the front-rear direction and configured so that filtered water filtered on the surface flows through the interior to the rear, and arranged at predetermined intervals from each other in the left-right direction; and a water collection unit connected to the rear end of each of the plurality of membrane elements for collecting filtered water flowing inside each membrane element, wherein the water collection unit has a horizontal passage extending along the direction of arrangement of the plurality of membrane elements and having a circular cross-section, and a vertical passage connected to the horizontal passage and extending in the vertical direction and having a circular cross-section, and the vertical passage is configured to communicate with the vertical passage of the water collection unit of other filtration modules arranged above and / or below. The transverse passages consist of an upper transverse passage and a lower transverse passage that are arranged to extend parallel to each other at a predetermined distance apart in the vertical direction, and the vertical passages consist of a plurality of vertical passages that are arranged to extend parallel to each other at a predetermined distance apart in the left-right direction, each of which communicates with the upper transverse passage and the lower transverse passage, and each of the plurality of membrane elements has an upper connecting part and a lower connecting part that communicates with the inside of the membrane element while connected to the upper transverse passage and the lower transverse passage, respectively, and the water collection parts are arranged on the left and right at a predetermined distance apart in the left-right direction, and The frame has a left frame section and a right frame section that extend vertically relative to each other, and its front shape is formed in the shape of a frame with a substantially rectangular shape; an upper horizontal pipe formed in the shape of a cylinder with an upper horizontal passage inside, and both ends connected to the left frame section and the right frame section, respectively; a lower horizontal pipe formed in the shape of a cylinder with a lower horizontal passage inside, and both ends connected to the left frame section and the right frame section, respectively, and positioned below the upper horizontal pipe; and a connecting wall positioned between the left frame section and the right frame section, connected to the upper horizontal pipe and the lower horizontal pipe, respectively, to connect these horizontal pipes. It is characterized by the following.

[0011] In this configuration, each filtration module of the filtration device comprises multiple flat membrane elements extending in the front-to-back direction, and a water collection section connected to the rear ends of these elements. Each membrane element is configured so that filtered water, filtered on its surface, flows through its interior to the rear, and these membrane elements are arranged at predetermined intervals from each other in the left-to-right direction. The water collection section is configured to collect the filtered water flowing through the interior of each membrane element. The filtration device is composed of multiple filtration modules, each comprising the above-described multiple membrane elements and water collection section, stacked in multiple layers in the vertical direction. In this filtration device, the water collection section of each filtration module has a lateral passage extending along the direction of arrangement of the multiple membrane elements, and a vertical passage connected thereto that extends vertically. Since both these lateral and vertical passages have a circular cross-section, compared to conventional water collection sections formed in a box shape, filtered water, washing water, or washing air can be efficiently flowed while suppressing the suction and pressing pressure acting on the water collection section during filtration and backwashing. As a result, the filtration function of the filtration device can be stably ensured over a long period of time. Furthermore, according to the above configuration, the water collection section of the filtration module is provided with an upper lateral passage and a lower lateral passage, which extend parallel to each other and at a predetermined distance in the vertical direction. The water collection section is also provided with a plurality of vertical passages that communicate with the upper lateral passage and the lower lateral passage. Each membrane element is provided with an upper connecting section and a lower connecting section that communicate with the interior of the membrane element, while being connected to the upper lateral passage and the lower lateral passage, respectively. During filtration, the filtered water from each membrane element flows into the upper and lower lateral passages of the water collection section via the upper and lower connecting parts of the membrane element. The filtered water then flows into the vertical passages of the water collection sections of other filtration modules via multiple vertical passages. During backwashing, the cleaning water and cleaning air sent into the vertical passages of the water collection sections of the filtration modules are sent into the upper and lower lateral passages of the water collection section, and further sent into the interior of each membrane element via the upper and lower connecting parts connected to those passages. In this way, during filtration and backwashing, the filtered water, cleaning water, or cleaning air can be efficiently flowed while suppressing the suction and pressure acting on the upper and lower lateral passages and multiple vertical passages of the water collection section. Furthermore, according to the above configuration, the water collection section further comprises the frame, upper and lower horizontal pipes, and a connecting wall. The connecting wall is positioned between the left and right frame sections of the frame, connected to the upper and lower horizontal pipes, respectively, to connect these horizontal pipes. By providing such a connecting wall, it is possible to suppress the flow of water to be treated (raw water) from the outside of the water collection section to the membrane element side. As a result, for example, if an aeration device for generating bubbles is placed below the filtration device and the filtration device is installed so as to be immersed in raw water, the bubbles from the aeration device will come into even contact with the surface of each membrane element, and as a result, clogging on the surface of the membrane elements can be effectively suppressed.

[0012] The invention according to claim 2 is a filtration device comprising a filtration module comprising: a plurality of membrane elements, each formed in a flat plate shape extending in the front-rear direction and configured so that filtered water filtered on the surface flows through the interior to the rear, and arranged at predetermined intervals from one another in the left-right and up-down directions; and a water collection unit connected to the rear end of each of the plurality of membrane elements for collecting filtered water flowing inside each membrane element, wherein the water collection unit comprises a horizontal passage extending along the left-right direction and having a circular cross-section, and a vertical passage connected to the horizontal passage and extending in the up-down direction and having a circular cross-section The transverse passages consist of an upper transverse passage and a lower transverse passage that are arranged to extend parallel to each other at a predetermined distance apart in the vertical direction, and the vertical passages consist of a plurality of vertical passages that are arranged to extend parallel to each other at a predetermined distance apart in the left-right direction, each of which communicates with the upper transverse passage and the lower transverse passage, and each of the plurality of membrane elements has an upper connecting part and a lower connecting part that communicates with the inside of the membrane element while connected to the upper transverse passage and the lower transverse passage, respectively, and the water collection parts are arranged on the left and right at a predetermined distance apart in the left-right direction. The frame has a left frame section and a right frame section that extend vertically relative to each other, and its front shape is formed in a frame shape that is approximately rectangular; an upper horizontal pipe formed in a cylindrical shape with an upper horizontal passage inside, and both ends connected to the left frame section and the right frame section, respectively; a lower horizontal pipe formed in a cylindrical shape with a lower horizontal passage inside, and both ends connected to the left frame section and the right frame section, respectively, and positioned below the upper horizontal pipe; and a connecting wall positioned between the left frame section and the right frame section, connected to the upper horizontal pipe and the lower horizontal pipe, respectively, to connect these horizontal pipes. It is characterized by the following.

[0013] According to this configuration, the filtration module as a filtration device comprises a plurality of flat membrane elements, each extending in the front-to-back direction, and a water collection section connected to the rear ends of these elements. Each membrane element is configured so that filtered water filtered on its surface flows through its interior to the rear, and these membrane elements are arranged at predetermined intervals from each other in the left-to-right and up-to-down directions. The water collection section, on the other hand, is configured to collect the filtered water flowing through the interior of each membrane element. In the filtration device consisting of the above-described filtration module, the water collection section has a lateral passage extending along the left-to-right direction and a vertical passage connected thereto that extends in the up-to-down direction. Since both these lateral and vertical passages have a circular cross-section, the filtration device of the present invention also has the same effects and advantages as described in claim 1 above, namely, it is possible to efficiently flow filtered water, washing water, or washing air while suppressing the suction and pressing pressure acting on the water collection section during filtration and backwashing, and to ensure stable filtration function over a long period of time. Furthermore, with the above configuration, similar to claim 1, filtered water, washing water, or washing air can be efficiently flowed while suppressing the suction and pressing pressure acting on the upper and lower lateral passages and multiple vertical passages of the water collection section during filtration and backwashing. Furthermore, according to the above configuration, clogging on the surface of the film element can be effectively suppressed, similar to claim 1.

[0019] Claim 3 The invention relating to this invention is characterized in that, in the filtration device described in claim 1 or 2, the water collection section is made of a molded product made of synthetic resin or a composite material using synthetic resin.

[0020] With this configuration, since the water collection section is made of a molded product made of synthetic resin or a composite material using synthetic resin, the water collection section can be manufactured relatively inexpensively and easily, thereby suppressing an increase in the manufacturing cost of the filtration module having a water collection section and the filtration device having multiple filtration modules. [Brief explanation of the drawing]

[0021] [Figure 1] This is an external perspective view showing a filtration device composed of multiple filtration modules, each having multiple membrane elements, stacked in a vertical configuration. [Figure 2]It is a diagram for explaining a filtration module, where (a) is an external perspective view and (b) is an exploded perspective view. [Figure 3] It is a diagram for explaining a membrane element, where (a) is a plan view, (b) is a front view, and (c) is a perspective view showing a part of the membrane element cut away. [Figure 4] (a), (b), and (c) respectively correspond to (a), (b), and (c) of FIG. 3, and are diagrams showing the flow of filtered water in the membrane element during filtration. [Figure 5] It is a diagram for explaining a water collection cassette, where (a) is an external perspective view, (b) is a front view, (c) is a cross-sectional view taken along the c-c line of the water collection cassette shown in (b), and (d) is a cross-sectional view taken along the d-d line of the water collection cassette shown in (b). [Figure 6] It is a front view showing the state of each water collection cassette when two filtration modules are stacked one above the other. [Figure 7] It is an explanatory diagram for explaining a method of replacing a membrane element, where (a) is a perspective view showing an upper unit of a filtration device, and (b) shows a state where a blind cover of a predetermined filtration module is removed. [Figure 8] It is an explanatory diagram following FIG. 7, where (a) shows a state where a single membrane element is removed, and (b) shows a state where a new membrane element is attached.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a filtration device 1 according to an embodiment of the present invention. This filtration device 1 is used, for example, in the case of purifying sewage or in the process of converting seawater into fresh water, when pre-treating seawater before sending it to a reverse osmosis membrane (a process of removing impurities from seawater to prevent clogging of the reverse osmosis membrane). It is used to obtain a desired filtered water by filtering the water to be treated (hereinafter referred to as "raw water").

[0023] As shown in Figure 1, the filtration device 1 is composed of multiple layers (10 layers in Figure 1) of filtration modules 2, each having a rectangular parallelepiped shape, stacked vertically. Although a detailed explanation is omitted, a diffuser 3 for generating bubbles is provided at the bottom layer of the filtration device 1. The filtration device 1 is installed so that the entire device is immersed in raw water, and by generating bubbles from the diffuser 3 during filtration, clogging of the membrane elements 4 of each filtration module 2 (described later) can be suppressed. In Figure 1, the filtration device 1 shows multiple filtration modules 2 stacked in a single vertical row, but it is also possible to configure a filtration device by arranging multiple rows (for example, 3 rows) of this filtration device 1 horizontally.

[0024] Figure 2 shows the filtration module 2, with (a) showing its external appearance and (b) showing it in a disassembled state. As shown in the figure, the filtration module 2 is equipped with a large number of membrane elements 4 (40 in Figure 2) arranged at predetermined intervals from one another in the left-right direction. In the following description, the entire group of membrane elements 4 in a single filtration module 2 will be referred to as "membrane element group 4A".

[0025] Furthermore, as shown in Figure 2(b), the filtration module 2 includes blind covers 5, a water collection cassette 6 (water collection section), and side covers 7L and 7R, which are positioned on the front, rear, and left and right sides of the membrane element group 4A, respectively. In addition, a membrane element group holder 8 is provided directly below the blind cover 5 to support the front end of the bottom surface of the membrane element group 4 from below, and a water collection cassette holder 9 is provided on the rear side of the water collection cassette 6 to support the water collection cassette 6 from behind. The water collection cassette 6 is made of synthetic resin or a composite material using synthetic resin. The blind cover 5, side covers 7L and 7R, membrane element group holder 8, and water collection cassette holder 9 are all made of synthetic resin or a composite material using synthetic resin, or metal or a material with a resin or synthetic resin coating on its surface. For synthetic resins, for example, polyvinyl chloride and ABS resin can be used, and for composite materials, FRP (fiber-reinforced plastic) such as GRP (glass fiber reinforced plastic) and CFRP (carbon fiber reinforced plastic) can be used.

[0026] Figure 3 shows the membrane element 4, where (a) is a plan view, (b) is a front view (right side view of membrane element group 4A), and (c) is a perspective view with a portion cut off. As shown in these figures, the membrane element 4 consists of a flat filter membrane 11 and a sealing side socket 12 and a suction side socket 13 attached to both ends of the filter membrane 11, respectively.

[0027] The filtration membrane 11 is made of ceramic and is formed in a horizontally elongated rectangular shape, as shown in Figures 3(a) and (b). This filtration membrane 11 has numerous pores (not shown), and inside it are multiple filtered water channels 11a (only seven shown in Figure 3(c)) that extend through in the length direction (left-right direction in Figure 3(b)) and are arranged side by side in the vertical direction.

[0028] Both the sealing-side socket 12 and the suction-side socket 13 are made of molded products of a predetermined shape made of synthetic resin. Specifically, the sealing-side socket 12 is formed so that the filtration membrane 11 side is open, and one end of the filtration membrane 11 (the left end in Figures 3(a) and (b)) is inserted into the opening and fixed to that end. In this way, the sealing-side socket 12 is attached to one end of the filtration membrane 11 so as to cover the entire membrane, and as a result, the openings at the corresponding ends of all filtered water channels 11a within the filtration membrane 11 are sealed. The sealing-side socket 12 is provided with two upper and lower protrusions 12a and 12b at predetermined positions in its longitudinal direction (up and down direction in Figure 3(b)) that slightly protrude on the side opposite to the filtration membrane 11.

[0029] On the other hand, the suction-side socket 13 is formed to have an opening on the side of the filter membrane 11, similar to the sealing-side socket 12 described above. The other end of the filter membrane 11 (the right end in Figures 3(a) and (b)) is inserted into the opening and fixed to the other end. The suction-side socket 13 is also provided with cylindrical outlet sections 13a and 13b at predetermined positions along its length, separated by a predetermined distance from each other and protruding on the side opposite to the filter membrane 11, for the purpose of discharging filtered water. The inner passages of these outlet sections 13a and 13b are connected to the opening of the suction-side socket 13.

[0030] Figures 4(a), (b), and (c) correspond to Figures 3(a), (b), and (c) described above, respectively, and show the flow of filtered water in the membrane element 4 during filtration. When negative pressure is applied to the outlets 13a and 13b of the suction socket 13 to perform filtration, as shown in Figure 4, the raw water indicated by the white arrows is filtered on the surface of the filtration membrane 11, and the filtered water flows into each filtered water channel 11a within the filtration membrane 11. The filtered water flows along each filtered water channel 11a as indicated by the arrows, passes through the suction socket 13, and flows out to the outside via the upper and lower outlets 13a and 13b.

[0031] Figure 5 shows the water collection cassette 6. As shown in Figures 5(a) and (b), the water collection cassette 6 is formed in the shape of a frame with a roughly horizontally elongated rectangular front shape and comprises a frame body 21 having a predetermined thickness and depth width, and inside the frame body 21, there are two horizontal pipes 31 and 32 that each extend in the left-right direction and are arranged at a predetermined distance from each other in the vertical direction, and three vertical pipes 41, 42, and 43 that each extend in the vertical direction and are arranged at a predetermined distance from each other in the left-right direction.

[0032] The frame 21 has an upper frame section 22 and a lower frame section 23 that are arranged vertically at a predetermined distance apart and extend parallel to each other in the left-right direction, and a left frame section 24 and a right frame section 25 that are arranged horizontally at a predetermined distance apart and extend parallel to each other in the vertical direction, connecting to the left ends and right ends of the upper frame section 22 and the lower frame section 23, respectively. The upper frame section 22 is provided with three openings 22a that open upward. The lower frame section 23 is provided with three openings 23a that open downward.

[0033] Both the upper horizontal pipe 31 and the lower horizontal pipe 32 are formed in a cylindrical shape and each has a horizontal passage 31a and 32a with a circular cross-section inside. Furthermore, both horizontal pipes 31 and 32 are configured so that both ends are connected to the left frame section 24 and the right frame section 25 of the frame body 21, respectively, thereby closing off both ends of the horizontal passages 31a and 32a.

[0034] Furthermore, both horizontal tubes 31 and 32 are provided with numerous connecting parts 33 and 34 (40 in Figures 5(a) and (b)) that connect to the upper and lower outflow parts 13a and 13b of the suction-side sockets 13 of each membrane element 4. Specifically, the upper horizontal tube 31 has numerous connecting parts 33 arranged in two rows, upper and lower, along the length of the horizontal tube 31, with a slight offset between them. Each connecting part 33 is formed in a cylindrical shape, with its inner passage 33a connected to the upper horizontal passage 31a. Similarly, the lower horizontal tube 32 has numerous cylindrical connecting parts 34 arranged in two rows, upper and lower, along the length of the horizontal tube 32, with a slight offset between them, and the inner passage 34a of each connecting part 34 connected to the lower horizontal passage 32a.

[0035] On the other hand, the three vertical pipes 41, 42, and 43 are all formed in a cylindrical shape and each has a vertical passage 41a, 42a, and 43a with a circular cross-section inside. Furthermore, these vertical pipes 41, 42, and 43 are all connected to the upper and lower horizontal pipes 31 and 32, traversing them, and are also connected to the upper frame portion 22 and the lower frame portion 23 of the frame body 21. As a result, the three vertical passages 41a, 42a, and 43a are connected to the upper and lower horizontal passages 31a and 32a, and their upper and lower ends are connected to the opening 22a of the upper frame portion 22 and the opening 23a of the lower frame portion 23, respectively.

[0036] Furthermore, in the water collection cassette 6, as shown in Figures 5(b) and (c), a connecting wall 45 is provided between the left frame portion 24 and the right frame portion 25, connected to the upper horizontal pipe 31 and the lower horizontal pipe 32, respectively, and arranged to connect these horizontal pipes 31 and 32. By providing such a connecting wall 45, it is possible to suppress the flow of raw water from the outside of the water collection cassette 6 (right side in Figure 5(c)) to the membrane element group 4A side (left side in Figure 5(c)), thereby ensuring that the bubbles from the aeration device 3 make even contact with the surface of the filtration membrane 11 of each membrane element 4, and as a result, clogging of the filtration membrane 11 can be effectively suppressed. Note that in the water collection cassette 6, the space between the upper frame portion 22 of the frame 21 and the upper horizontal pipe 31, and the space between the lower frame portion 23 of the frame 21 and the lower horizontal pipe 32 are open.

[0037] Figure 6 shows the connection between the two water collection cassettes 6 when two filtration modules 2, 2 are stacked vertically. As shown in the figure, in this case, cylindrical connecting tubes 47 having a predetermined diameter and length are fitted into the openings 22a, 23a that are facing each other vertically in order to connect the openings 22a, 22a of the upper frame portion 22 of the lower water collection cassette 6 with the openings 23a of the lower frame portion 23 of the upper water collection cassette 6. As a result, the vertical passages 41a, 42a, and 43a of the upper and lower water collection cassettes 6, 6 are connected to each other.

[0038] In the filtration module 2 configured as described above, the membrane element 4 and water collection cassette 6 are connected by inserting the upper and lower outlet portions 13a and 13b of the suction-side socket 13 of the membrane element 4 into the upper and lower connecting portions 33 and 34 of the water collection cassette 6. This connects the filtered water passages 11a in the filtration membrane 11 of the membrane element 4 with the upper and lower lateral passages 31a and 32a of the water collection cassette 6.

[0039] Furthermore, as shown in Figures 1 and 2, each filtration module 2 is fixed to support columns 50 located at the four corners of the filtration device 1 via a blind cover 5, left and right side covers 7L and 7R, and a water collection cassette holder 9. Specifically, left and right front support columns 51L and 51R, and left and right rear support columns 52L and 52R are located at a predetermined distance apart in the left-right direction on the front and rear sides of the filtration device 1. In the following description, unless otherwise specified, these front support columns 51L and 51R and rear support columns 52L and 52R will simply be referred to as support columns 50.

[0040] These support columns 50 are made of synthetic resin or a composite material using synthetic resin, or metal or a metal coated with resin or synthetic resin, and extend a predetermined length in the vertical direction, with a cross-section that is roughly U-shaped. The four support columns 50 are arranged such that the cross-sections of the left and right support columns 50 50 are symmetrical from left to right, and the cross-sections of the front and back support columns 50 50 are symmetrical from front to back.

[0041] As shown in Figure 2, the blind cover 5 has a horizontally elongated rectangular shape at its front and is formed as a plate that covers the entire front surface of the membrane element group 4A. The left and right ends of the blind cover 5 are provided with left and right mounting portions 5L and 5R, respectively, which protrude forward and whose front ends are bent outward in the left-right direction. These left and right mounting portions 5L and 5R are then screwed to the left and right front support columns 51L and 51R, respectively.

[0042] The left and right side covers 7L and 7R are horizontally elongated rectangular in shape and are formed as plates that cover the entire side surface of the membrane element group 4A. The outer periphery of the side covers 7L and 7R is formed to bend outward in the left-right direction, and mounting parts 7F and 7B are provided at the front and rear ends, respectively. The front and rear mounting parts 7F and 7B of the left side cover 7L are screwed to the left front support column 51L and the left rear support column 52L, respectively. On the other hand, the front and rear mounting parts 7F and 7B of the right side cover 7R are screwed to the right front support column 51R and the right rear support column 52R, respectively.

[0043] The water collection cassette holder 9 has a horizontally elongated rectangular shape on its front and is formed in a predetermined shape to engage with the water collection cassette 6 from the rear side. In addition, mounting parts 9L and 9R are provided at both the left and right ends of the water collection cassette holder 9, which protrude outward in the left and right directions from the water collection cassette 6. These left and right mounting parts 9L and 9R are then screwed to the left and right rear support columns 52L and 52R, respectively.

[0044] In the filtration device 1 configured as described above, the filtration device 1 is installed so as to be immersed in raw water, and a pump (not shown) is connected to the three openings 22a of the water collection cassette 6 of the uppermost filtration module 2. During filtration, the pump applies negative pressure to the filtration device 1, so that the filtered water filtered by each membrane element 4 in all filtration modules 2 is collected in the two horizontal passages 31a and 32a of the water collection cassette 6, and then transported upward through the three vertical passages 41a, 42a, and 43a. The filtered water discharged from the water collection cassette 6 of the uppermost filtration module 2 is stored in a storage tank or the like, which is installed outside the filtration device 1.

[0045] On the other hand, during backwashing, the pump is rotated in the opposite direction to that used during filtration, thereby sending cleaning water or cleaning air to the water collection cassette 6 of the uppermost filtration module 2. As a result, in all filtration modules 2, cleaning water or cleaning air is sent through the vertical passages 41a, 42a, 43a and horizontal passages 31a, 32a of the water collection cassette 6 to the filtered water flow path 11a within each membrane element 4. This prevents clogging of the filtration membrane 11 in each membrane element 4.

[0046] Next, with reference to Figures 7 and 8, a method for replacing the membrane element 4 in any filtration module 2 during maintenance of the filtration device 1 will be described. Figure 7(a) shows the upper unit that constitutes the upper half of the filtration device 1. In this filtration device 1, for example, when replacing the membrane element 4 of the third filtration module 2 from the top, the replacement work is performed as follows.

[0047] First, as shown in Figure 7(b), the blind cover 5 of the filtration module 2 is removed from the filtration device 1. Specifically, the blind cover 5 is removed from the left and right front supports 51L and 51R by removing the mounting screws from the left and right mounting parts 5L and 5R of the blind cover 5. When replacing the membrane element 4, only the blind cover 5 is removed from the filtration module 2, and the membrane element group holder 8 that supports the lower front end of the membrane element group 4A from below is left in place.

[0048] Next, the protective plate 61 is inserted from the side of the filtration device 1 (to the right in Figure 7(b)) and installed between the upper and / or lower filtration modules 2. The protective plate 61 has a flat body portion 62 of a predetermined size that can partition the entire membrane element groups 4A, 4A of the upper and lower filtration modules 2, 2 vertically, and a handle 63 is provided at the end of the body portion 62. This protective plate 61 (61U) is installed, for example, between the second and third filtration modules 2 from the top, specifically, in the gap between the right side covers 7R of both filtration modules 2, 2, from the right. Similarly, another protective plate 61 (61D) is installed by inserting it between the third and fourth filtration modules 2 from the top.

[0049] Figure 8(a) shows the two protective plates 61U and 61D installed above and below the third filtration module 2 from the top. From this position, the membrane element 4 to be replaced is pulled out while moving it forward. In this case, the upper and lower outlets 13a and 13b of the suction-side socket 13 of the membrane element 4 are pulled out from the upper and lower connecting parts 33 and 34 provided on the upper and lower horizontal pipes 31 and 32 of the water collection cassette 6.

[0050] Then, in the space left by the removal of the membrane element 4 from the membrane element group 4A, a new membrane element 4 is moved from front to back, and the outlet portions 13a and 13b of the suction-side socket 13 of the membrane element 4 are inserted into the connecting portions 33 and 34 of the horizontal pipes 31 and 32 of the water collection cassette 6. This connects the new membrane element 4 to the water collection cassette 6.

[0051] In the filtration module 2 described above, after all membrane elements 4 to be replaced have been replaced, the two protective plates 61U and 61D are pulled out and removed from the filtration device 1, as shown in Figure 7(a) above, and the removed blind cover 5 is screwed to the left and right front supports 51L and 51R and attached to the filtration device 1. With this, the replacement work of the membrane elements 4 in the filtration module 2 is completed.

[0052] As described in detail above, according to this embodiment, the water collection cassette 6 of each filtration module 2 in the filtration device 1 has two horizontal passages 31a, 32a and three vertical passages 41a, 42a, 43a. Since the horizontal passages 31a, 32a and the vertical passages 41a, 42a, 43a all have a circular cross-section, filtered water, washing water, or washing air can be efficiently flowed while suppressing the suction and pressing pressure acting on the water collection cassette 6 during filtration and backwashing. As a result, the filtration function of the filtration device 1 can be stably ensured over a long period of time.

[0053] Furthermore, when replacing the membrane element 4 during maintenance of the filtration device 1, the blind cover 5 is removed from the filtration module 2 having the membrane element 4 to be replaced, and the membrane element 4 is attached to and detached from the water collection cassette 6 while moving it in the front-back direction. This allows for easy replacement of the membrane element 4 of any filtration module 2 in the filtration device 1. In addition, when replacing the membrane element 4, a protective plate 61 is inserted from the outside between the filtration module 2 having the membrane element 4 and the upper filtration module 2, and / or the lower filtration module 2, thereby preventing the membrane element 4 from coming into contact with the membrane element 4 of the upper or lower filtration module 2 during replacement. This allows for proper replacement of the membrane element 4 without damaging the membrane element 4 itself or the membrane elements 4 of the upper or lower filtration modules 2.

[0054] It should be noted that the present invention is not limited to the embodiments described above and can be implemented in various forms. In the embodiments, the filtration device 1 was constructed by stacking multiple filtration modules 2 in the vertical direction, but it is also possible to construct a filtration module by constructing multiple (for example, three) water collection cassettes 6 from a single molded product, and connecting multiple membrane elements 4 to such water collection cassettes in a state where they are arranged not only in the left-right direction but also in the vertical direction. A filtration device consisting of such a filtration module can also obtain the same functions and effects as the filtration device 1 described above.

[0055] Furthermore, in this embodiment, cylindrical shapes were used for the horizontal pipes 31, 32 and vertical pipes 41, 42, 43 of the water collection cassette 6. However, the cross-section of the internal passages (horizontal passages 31a, 32a and vertical passages 41a, 42a, 43a) only needs to be circular, and the external shape of the horizontal pipes 31, 32 and vertical pipes 41, 42, 43 is not particularly limited, and the cross-section may be a shape other than circular. In addition, in the protective plate 61 used when replacing the membrane element 4, a number of guide grooves corresponding to a number of membrane elements 4 and extending parallel to each other in the front-to-back direction may be provided on the front and back surfaces of the main body 62. In this case, when replacing the membrane element 4, the membrane element 4 can be moved smoothly and stably in the front-to-back direction by moving it along the corresponding guide groove.

[0056] Furthermore, among the various components constituting the filtration device 1, components other than the ceramic filtration membrane 11 can be made of synthetic resin or composite materials using synthetic resin, or of metal or a metal coated with resin or synthetic resin. In particular, by making these components of materials with high corrosion resistance to seawater, the filtration device 1 can be used for a long period of time even when immersed in seawater. Also, the detailed configurations of the filtration device 1, filtration module 2, membrane element 4 and water collection cassette 6 shown in the embodiment are merely examples and can be appropriately modified within the scope of the present invention. [Explanation of symbols]

[0057] 1 Filtration device 2 Filtration Modules 4 membrane elements 4A Film element group 5 Blind Cover 6. Water collection cassette (water collection section) 7L Left side cover 7R Right side cover 8. Film element group holder 9. Water collection cassette holder 11 Filtration membrane 11a Filtered water channel 12. Socket on the sealing side 13 Suction side socket 13a Upper outflow section (upper connecting section) 13b Lower outflow section (lower connecting section) 21 Frame 22 Upper frame 22a Opening of the upper frame 23 Lower frame part 23a Opening of the lower frame 31 Upper horizontal tube 31a Upper lateral passage 32 Lower horizontal tube 32a Lower side passage 33. Connection part of the upper horizontal pipe 34. Connection of the lower horizontal pipe 41. Left vertical pipe 41a Left-hand vertical passage 42 Central vertical pipe 42a Central vertical aisle 43 Right vertical pipe 43a Right-hand vertical aisle 47 Connecting tube 50 pillars 51L Left front support 51R Right front support 52L Left rear support 52R Right rear support 61 Protective plate

Claims

1. Each of the membrane elements is formed as a flat plate extending in the front-to-back direction, and is configured so that filtered water filtered on the surface flows through the interior to the rear, and is arranged at predetermined intervals from each other in the left-to-right direction. A water collection unit is connected to the rear end of each of the plurality of membrane elements for collecting filtered water flowing inside each membrane element, In a filtration device configured by stacking multiple filtration modules equipped with the above in a vertical direction, The aforementioned water collection section is A transverse passage extending along the arrangement direction of the plurality of membrane elements and having a circular cross-section, A vertical passage is connected to the horizontal passage and extends vertically, with a circular cross-section, It has, The aforementioned vertical passage is configured to communicate with the vertical passages of the water collection sections of other filtration modules located above and / or below. The aforementioned lateral passage includes an upper lateral passage and a lower lateral passage that are arranged to extend parallel to each other and at a predetermined distance apart in the vertical direction. The aforementioned vertical passages are arranged so as to extend parallel to each other at a predetermined distance in the left-right direction, and each is composed of multiple vertical passages that communicate with the upper horizontal passage and the lower horizontal passage. Each of the plurality of membrane elements has an upper connecting portion and a lower connecting portion that communicate with the interior of the membrane element, while being connected to the upper lateral passage and the lower lateral passage, respectively. The aforementioned water collection section is A frame body having a left frame section and a right frame section arranged on the left and right sides separated by a predetermined distance in the left-right direction and extending vertically from each other, with a front shape formed in a substantially rectangular frame shape, The upper horizontal tube is formed in a cylindrical shape having the aforementioned upper horizontal passage inside, with both ends connected to the left frame and the right frame, respectively. A cylindrical shape having the aforementioned lower horizontal passage inside, with both ends connected to the left frame and the right frame respectively, and a lower horizontal tube positioned below the upper horizontal tube, Between the left frame and the right frame, a connecting wall is positioned to connect the upper horizontal pipe and the lower horizontal pipe, respectively, and these horizontal pipes are connected to each other. A filtration device characterized by further having

2. Each of the membrane elements is formed as a flat plate extending in the front-to-back direction, and is configured so that filtered water filtered on the surface flows through the interior to the rear, and is arranged at predetermined intervals from each other in the left-to-right and up-to-down directions. A water collection unit is connected to the rear end of each of the plurality of membrane elements for collecting filtered water flowing inside each membrane element, In a filtration device comprising a filtration module equipped with, The aforementioned water collection section is A transverse passage extending in the left-right direction, with a circular cross-section, A vertical passage is connected to the horizontal passage and extends vertically, with a circular cross-section, It has, The aforementioned lateral passage includes an upper lateral passage and a lower lateral passage that are arranged to extend parallel to each other and at a predetermined distance apart in the vertical direction. The aforementioned vertical passages are arranged so as to extend parallel to each other at a predetermined distance in the left-right direction, and each is composed of multiple vertical passages that communicate with the upper horizontal passage and the lower horizontal passage. Each of the plurality of membrane elements has an upper connecting portion and a lower connecting portion that communicate with the interior of the membrane element, while being connected to the upper lateral passage and the lower lateral passage, respectively. The aforementioned water collection section is A frame body having a left frame section and a right frame section arranged on the left and right sides separated by a predetermined distance in the left-right direction and extending vertically from each other, with a front shape formed in a substantially rectangular frame shape, The upper horizontal tube is formed in a cylindrical shape having the aforementioned upper horizontal passage inside, with both ends connected to the left frame and the right frame, respectively. A cylindrical shape having the aforementioned lower horizontal passage inside, with both ends connected to the left frame and the right frame respectively, and a lower horizontal tube positioned below the upper horizontal tube, Between the left frame and the right frame, a connecting wall is positioned to connect the upper horizontal pipe and the lower horizontal pipe, respectively, and these horizontal pipes are connected to each other. A filtration device characterized by further having

3. The filtration device according to claim 1 or 2, characterized in that the water collection section is made of a molded product made of synthetic resin or a composite material using synthetic resin.

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